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UNITED STATES PATENT CFFICE,

FRANK L. SLOCUMAND HORACE XV. LASH, OF PITTSBURG, PENNSYLVANIA, ASSIGNORS TO THOMAS J. MOTIGHE, OF NEW YORK, N. Y., AND SAID FRANK L. SLOCUM, TRUSTEES.

PROCESS OF TREATING MOLTEN METAL WITH NATURAL GAS.

SPECIFICATION forming part of Letters Patent No. 411,205, dated September 17, 1889.

Application filed March 15, 1886.

To all whom it may concern.-

Be it known that we, FRANK L. SLOCUM and HORACE W. LAsH, of Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvementin the Process of Treating Molten Metals with Natural Gas and we do hereby declare the following to be a full, clear, and exact description thereof.

Our invention relates to the treatment of molten iron, steel, and other metals or alloys for the formation of carbides thereof and the purification thereof from admixed elements or compounds, as well as the removal of free orcombined oxygen therefrom, its special obj ect being to deoxidize, purify, and carburize molten iron in the manufacture of all classes of steel or iron, whether crucible, open-hearth, creme, Bessemer, or other steels, as well as to obtain any degree of carbon in the resultant metal from puddled iron containing but a trace thereof to the highest percentage required. It may also be employed to advantage in the manufacture of diiferent alloys, such as self'hardening steel, phosphor-bronze, carbon-bronze, manganese-irou bronze, the.

Our invention relates specially to the use of natural gas or methane to deoxidize the metal to purify the same by removing therefrom the sulphur and other impurities, and to form a carbide with or recarburize the metal, raising it to the required percentage of carbon.

Ourinvention consists in heating the natural gas or methane to a point below the temperature at which it decomposes, and then passing the heated natural gas through the metal when in a molten condition, so providing for the treatment of the molten metal without chilling it or reducing it in fluidity, and enabling us to control better the treatment of the metal for deoxidizing, purifying, and recarburizing, as may be found necessary.

To enable others skilled in the art to make and use our invention, we will describe the same more fully.

Our invention can be practiced with any of the ordinary furnaces or other apparatus en1- Serial Nol95,327. (No model.)

ployed with the different processes of manufacturing iron, steel, or other metals with which it is employed, and for this reason we have not illustrated the same. In the manufacture of steel by the Bessemer and kindred processes, our invention may be employed in the following manner: The molten pig metal is charged into the converter in the ordinary manner and the ordinary air-blast forced through it to remove the carbon and other impurities, this being commonly termed decarburizing. The natural gas employed for treating the metal decomposes at a lower heat than the melting-point of the metal, and yet can be raised to a comparatively high heat before it is decomposed, and can therefore be so heated as to prevent the chilling of the metal and decreasing its fluidity when introduced, which would take place if the cold gas were introduced and necessarily absorbed from the metal sufficient heat to cause the decomposition of the gas, as has been practically proven. For the purpose of heating the gas we employ any suitable form of hotblast oven, which it is not considered necessary to illustrate. The gas is heated to any point below that of its decompositionsay about 1,500 centigrade-before it is forced through the molten metal within the converter, being introduced through the ordinary tuyeres, and being forced through the metal either by its natural pressure or under artificial pressure, as may be found necessary. As so introduced, the gas is quickly decomposed by the molten metal without reducing the temperature thereof to any appreciable extent, the gas being decomposed into hydrogen and carbon. oxidize the metal, the hydrogen uniting with the oxygen therein to form steam, and the carbon uniting therewith to form carbonic oxide, both of which pass off in gaseous form. lVhere the molten metal contains any sulphur, the hydrogen will unite therewith to form sulphureted hydrogen, or, under certain circum stances, the carbon will unite with the sul phur to form bisnlphideof carbon and pass off in a gaseous form. There the metal contains phosphorus, a portion thereof will unite These gases first act to dewith the hydrogen and pass off as phosphoreted hydrogen; but, so far as now known, all the phosphorus cannot be eliminated in this manner. As the stream of gas continues, the free carbon in an amorphous state at a regular speed unites with the molten metal to carburize it, or otherwise form carbide of iron or steel. The decomposition of the gas takes place regularly and quietly, while the heat generated by the chemical actions, aided by the lowering of the melting-point of the metal by the addition of carbon thereto, keeps the bath in a highly liquid state. The current of gas is continued until the desired percentage of carbon is obtained therein, this being ascertained by tests, as usual, and the metal is then ready to pour. Theresultant product is a true steel practically free from oxygen or oxides and raised to the percentage of carbon required.

In employing our invention in connection with the open-hearth and kindred processes of making steel of homogeneous iron, the heated natural gas may be introducedinto and caused to pass upwardly through the bath of decarburized molten metal by means of one or more movable tuyeres entering through the roof, door, or side walls of the furnace, and the process and results obtained are substantially the same as when used in the Besssemer process, as above described.

The steel so produced in either the open hearth or converter is practically of as fine quality as the ordinary crucible steel, and may be employed for substantially all the uses of such-steel. If, however, our improvements are to be applied to crucibl'e steel, after it is melted in the crucible it may be teemed into a ladle or converter and the heated gas passed through it to thoroughly deoxidize and purify it.

In employing our invention in the manufacture of alloys, its advantages may be illustrated in the manufacture of manganese-iron bronze, which has heretofore been exceedingly difficult to obtain without the admixture of slag or scoria on account of its liability to oxidize. The ferro-manganese and copper may be melted together in the proper proportions without regard to their oxidation, and when melted the heated natural gas passed through the molten metal, the gas decomposing when in contact with and at the heat of the metals and acting to thoroughly deoxidize them, in which condition they will alloy perfectly.

I By heating the natural gas or methane before introducing it into the molten metal, we are enabled to produce better results than by the introduction of the gas when cold, as the metal can be maintained at a higher temperature and its fluidity assured even when very low in carbon.

that we claim as our invention, and desire to secure by Letters Patent, is

The herein-described improvement in the art of treating metals, consisting in heating natural gas or methane to a point below the temperature at which it decomposes, and then passing it through the metals when in a molten condition, substantially as and for the purposes set forth.

In testimony whereof we, the said FRANK L. SLooUM and HORACE \V. LASH, have hereunto set our hands.

FRANK L. SLOCUM. HORACE w. LASH.

lVitnesses:

.TAMEs I. KAY, I. E. BARNES. 

